Ask a local gym rat, athlete or body builder how strong they are and you usually get a response about how much they can bench press. When was the last time you ever heard them talk about grip strength? Grip strength plays a huge role in the success of many sports but yet is highly neglected in most strength and conditioning programs.
Grip strength is the limiting factor of how much weight can be lifted, for example in the pull up. Most people fail at pull-ups not because of back strength, but because their grip strength is insufficient. To compensate, many athletes use wrist wraps.